CTLA4 and classic Hodgkin lymphoma: Another actor in the cHL immunosuppressive TME is the Treg population, characterized by the expression of CD4, CD25high, CD127low (IL-7R), forkhead box protein 3 (FoxP3), cytotoxic T lymphocyte associated protein 4 (CTLA-4), CD73, and CD39, and by an immunosuppressive capacity [125,126].